Summary:
The SspA protein is associated with RNA polymerase [Williams94] and is required for transcriptional activation of the bacteriophage P1 late promoter in vivo and in vitro [Hansen03b]. SspA is essential for cell survival during acid-induced stress, acting by inhibiting accumulation of the global regulator H-NS during stationary phase [Hansen05].

SspA expression is induced by starvation for glucose, nitrogen, phosphate or amino acids, and it increases with decreasing growth rate [Williams94a].

The SspA protein has been crystallized, but the crystals did not allow structure determination [Andrykovitch03]. Determination of a crystal structure was attempted with SspA proteins from Vibrio cholerae, Pseudomonas aeruginosa, and Yersinia pestis; only the Y. pestis protein diffracted to 2.0 A [Andrykovitch03]. High sequence conservation allows modelling of the E. coli protein on the basis of the Y. pestis SspA crystal structure, and amino acid residues of potential functional importance have been mutagenized [Hansen05a].

Deletion of the sspA gene results in decreased long-term viability under arginine starvation conditions. During exponential growth, expression of at least 11 proteins is altered in the mutant. relA is required for the effect of sspA on protein synthesis [Williams94a].